Apparatus for testing the tensile strength of flexible materials



APPARATUS FOR TESTING THE TENSILE STRENGTH 0F FLEXIBLE MATERIALS March 24, 1931. A. SCHOPPER Filed March 8. 1929 Patented Mar. 24, '1931 ALFRED SCHOPPER, OF LEIPZIG, sum/zany, nssrenor. TQ FIRM Louis sonorrnn,

on intr nsic, GERMANY APPARATUS FOR TESTING THE TENSILE STRENGTH F FLEXIBLE MATERIALS Application filed March 8, 1929, Serial No. 345,505, and inGerinany February 1, 1927.

Myv invention relates to apparatus for testing the tensile strength of flexible materials by inflation. It is an object of myinvention to provide an apparatusin which the area '5; subjected to inflating pressure may be varied.

To this end I provide exchangeable parts for supporting the part to be tested.

In an apparatus embodying my invention the part under test which is inflated by gas under pressure is held between a plate and a cup-shaped jaw. By providing exchangeable parts as explained above, the area subjected to pressure may be varied so that, for

instance, parts of high tensile strength may be tested under comparatively low air pressure. it

In order to obtain uniform contact at the areas where the part under test is held, I may provide a resilient insertion for one of the parts.

In the drawings afiixed to this specification and forming part thereof apparatus embodying my invention is illustrated diagrammatically by way of example.

In the drawings Fig. 1 is an elevation of a testing apparatus, partly in section,

Fig. 2 is an elevation, also partly in section,

showing part of an apparatuswhich has been modified for the testing of very permeable materials.

Referring now to the drawings, (Z is the foundation plate of the apparatus to which a yoke 12 is secured. is an anvil plate inserted in the foundation plate (Z, c is the aforementioned resilient insertion below the anvil plate 0 which must not I be confused with the resilient packing ring provided in apparatus for testingthe permeability of leather and other materials, 2) is a cup-shaped jaw adapted to hold the part a down on the anvil plate 0, g is a threaded spindle in the yoke 12, and f is a handwheel for rotating the spindle. The cup-shaped jaw 71 is detachably secured to the end of the spindle g and held thereon by a screw 0 so that it may be readily exchanged in order to vary the area under pressure for the object specified. 7) is a plunger adapted to engage the part a on its convex sideso as to bedisplac'ed in cona is the part under test, 0

formity with its inflation and to operate a gauge, not shown, for measuring the camber of the inflated part.

Q is a passage in the foundation plate d, the insertion e and the anvil plate 0, and a source of gas or air under pressure, not shown, is connected to the passage g. 1 is a bore in the foundation plate which connects the passage qwitha pressure gauge 8.

. operation, pressure is admitted to the space below the part a and the. part is inflated until it bursts, its camber being measured by the gauge connected with the plunger 2.

With highly permeable materials the loss of air percolating through the pores of the part under test isso considerable as to interfere with the testing. In order to prevent this, a film 7L of impermeable material, such as rubber, is inserted between the part a and the anvilplate 2' on whichcthe part'under test is held-by the jaw '7) as shown in Fig. 2. The anvil plate e' corresponds to the plate 0, Fig. 1, and is also supported on a resilient insertion 6, but it is annular and provided with a solid inserted plate in by which the film it is, held on the, preferably tapering, faces of the plates 2" and 70. As shown in Fig. 2 the edge of the film it is turned over. about the face of the plate is so that it is held under tension when the plate isin position, and it is not necessary to smooth the film before the test. p e I It is not indispensable that the film should be secured inthe manner described but it may be. siinplyplaced below the part a on the undivided anvil plate 0 as in Fig. 1.

In order to readily return thefilm h to its initial position after each test, a passage Z may be connected with the passage 9 and provided with a cock m through which the air. below the filmh is. discharged.

It is understood that not only the jaw b but also the plates 0, i and 70 may be exchangeable,

I wish it to be understood that I do notno selection of any particular modification of the invention is intended to the exclusion of other modifications thereof and the rightto subsequently'make claim to any modification not covered by these claims is expressly reserved.

I claim 1. An apparatus for testing th tensile strength of flexible materials by inflation comprising means for supplf under pressure to one of the part ander test, and exchangeable means of geometrica ly similar configuration for holding said pa. e.

2. An apparatus for testing the tensile strength of flexible materials by inflation comprising means for supplying gas under pressure to one side ot the part under test, a foundation plate, exchangeable means of geometrically similar Configuration for holding said part, and a resilient insertion between one of said means and said foundation plate.

3. An apparatus for tes ing the tensile strength of flexible materials by'inflation comprising means for supplying gas under pressure to one side of the part under test, a foundation vplate, exchangeable means of geometrically similar configuration for holding said part comprising an anvil plate inserted in said foundationplate, and a re silient insertion between said anvil and said foundation plate.

42. An apparatus for testing the tensile strength of flexible materials by inflation comprising means for supplying gas under pressure to one side of the part under test, an exchangeable cup-shaped 3aW adapted to engage said part on one side, and a resilient support on the other side.

5. An apparatus for testing the tensile strength of flexible materials by inflation comprising means for supplying gas under pressure "to. one side of the part under test, exchangeable means for holding said part, and a fllni or" impermeable material applied to one side of said part.

6. An apparatus for testing the tensile strength of flexible materials by inflation comprising means for supplying gas under pressure to one side of the part under test, a roundation plate, an anvil plate inserted in said foundation plate, and means for securing a film of impermeable material to said anvil plate. V

7. An apparatus for testing the tensile strength of flexible materials by inflation comprising means for supplying gas under pressure to one side of the part under test, a foundation plate, an annular anvil plate inserted in said foundation plate, a plate adapted to be inserted in said annular anvil plate, and a iilm of impermeable material on said inserted plate, the edge of said film being held between the mating faces of said annular anvil plate and said inserted plate.

ALFRED soirorrnn.

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